A hiccup is a spasmodic inhalation resulting from an involuntary spasm of the diaphragm followed by the closure of the glottis, thus checking air inflow and producing a familiar and characteristic sound. Although the anatomic mechanism responsible for producing hiccups remains unknown, a hiccup reflex arc has been proposed to account for what little is known about the pathophysiology of hiccups. See, for example, "Hiccups," P. Rosseau, M.D., Southern Medical Journal, Vol., 88, pp. 175-181, 1995. Briefly, the reflexive arc includes afferent and efferent branches that are centrally connected between cervical segments 3 and 5. The afferent branch is believed to encompass the phrenic, vagus, and T6 to T12 sympathetic nerve fibers, as well as a hiccup center located either in the brain stem and/or the respiratory center. The phrenic nerve serves as the principal efferent limb of the arc. Reflexive discharge of the phrenic nerve results in spasmodic contraction of the diaphragm, thus producing a hiccup.
Hiccups have been classified according to the length of their duration. Episodes lasting up to 48 hours are "hiccup bouts," hiccups continuing for longer than 48 hours are termed "persistent," and hiccups lasting longer than one month are referred to as "intractable." While hiccup bouts may be bothersome, persistent and intractable hiccups may have significant adverse effects including malnutrition, weight loss, fatigue, exhaustion, dehydration, cardiac dysrhythmias, wound dehiscence, insomnia, and in the extreme, death.
Although some causes of hiccups are not apparent, the cause of frequent or prolonged hiccup attacks may often be determined. In fact, more than one hundred causes of persistent hiccups are known. In some instances, hiccups are a symptom of an underlying disorder.
Hiccups can result from afferent nerve stimulation as a consequence of swallowing hot or irritating substances. Hiccups have also been known to accompany diaphragmatic pleurisy, pneumonia, uremia, alcoholism, and some abdominal surgical procedures. Hiccups may also be caused by abdominal disorders including disorders of the stomach and esophagus, bowel diseases, pancreatitis, bladder irritation, hepatic metastases, and hepatitis, among others.
Treatments for hiccups are numerous and varied, and include both anecdotal and scientific cures, with each achieving varying degrees of success. Many individuals have their own favorite remedies for hiccups. Suddenly frightening someone suffering from hiccups is commonly believed to be effective in "scaring away" hiccups. Drinking a glass of water while upside-down is another commonly practiced treatment by hiccup sufferers.
Other hiccup treatments include more scientific approaches. For example, while low blood levels of carbon dioxide have been found to accentuate hiccups, high carbon dioxide blood levels tend to have an inhibiting effect on hiccups. Accordingly, simple measures to increase blood carbon dioxide levels and decrease diaphragmatic activity include repetitive deep breath holding or rebreathing deeply into a paper bag. Vagal stimulation (i.e., stimulation of the viscus, an internal organ in the body such as the stomach) has been recommended as a treatment. Such stimulation may include rapidly drinking a glass of water, swallowing dry bread or crushed ice, inducing vomiting, applying traction on the tongue, and applying pressure on the eyeballs. In addition, massage techniques, such as carotid sinus compression and digital pressure applied over the phrenic nerves behind the sternoclavicular joints, have also been suggested as hiccup treatments.
Other more extreme maneuvers include gastric lavage, galvanic stimulation of the phrenic nerve, and esophageal dilation. These procedures are invasive and are undertaken only by medical professionals. To prevent injury or reinjury or aggravation of a condition, inhalation of oxygen containing carbon dioxide has been noted as valuable in inhibiting hiccups in post-operative patients. For sufferers of diaphragmatic pleurisy, tight adhesive support of the lower chest is thought to be helpful.
In addition to the treatments noted above, pharmacological agents have been administered and have gained widespread use in treating persistent hiccups. Commonly administered drugs include chlorpromazine, haloperidol, diphenylhydantoin, valproic acid, carbamazepine, amitriptyline, scopolamine, amphetamine, prochlorperazine, phenobarbital, metoclopramide, as well as some narcotics. As the length of the above list of drugs implies, successful treatment of hiccups by the administration of drugs is often elusive.
Methods that disrupt phrenic nerve transmission have been reported to be successful hiccup treatments. These methods range from simple rhythmic tapping over the fifth cervical vertebra at the level of the origin of the phrenic nerve, electrical stimulation, and anesthetic injection, to surgical transection of the phrenic nerve. Surprisingly, it has been noted that even bilateral phrenicotomy, surgical division of the phrenic nerve, does not cure all cases of hiccups.
Other methods that have been reported to successfully treat hiccups include cooling treatments. For example, the application of vapocoolant sprays over the skin representing the muscles associated with the hiccup reflex, particularly regions of the lower thoracic and upper lumbar regions across the back, have been reported to block myofascial reflex and relieve hiccuping. Ether spray on the epigastrium has also been suggested as a hiccup cure. Placing ice inside the mouth to cool the uvula, a purported trigger point for hiccups, has also been reported to be an effective hiccup treatment.
Cooling treatments directed to the neck, and indirectly to the phrenic nerve, have also been suggested as hiccup treatments. The application of ice bags, mustard paste, and ethyl chloride sprays either on the back of the neck along the course of the phrenic nerves, or over the area of the insertion of the diaphragm have been found to be effective in certain cases ("Hiccup," E. C. Noble, Can. Med Assc. J, Vol. 33, pp. 38-41, 1934). The application of ice packs to the sides of the neck has also been reported ("Hiccoughing," N. G. Hulbert, Practitioner, Vol. 167, pp. 286-289, 1951). However, the effectiveness of cooling sprays applied to the neck, chest, and epigastrium for the treatment of hiccups has been called into question ("A Trigger Point for Hiccup," J. G. Travell, J. Am. Osteopath. Assc., Vol. 77, pp. 308-312, 1977).
The breadth and diversity of the treatments noted above vividly illustrate that no single treatment has been demonstrated to be reliably effective in treating hiccups. Accordingly, there remains a need in the art for a simple, effective, reliable, and safe treatment for hiccups. The present invention seeks to fulfill this need and provides further related advantages.